(1) Field of the Invention
This invention relates to a guidance system for agricultural land tractors and more particularly to that part of the system which senses the stalks along the rows which the tractor is to follow particularly in harvesting the crop. Farmers raising row crops are those having ordinary skill in the art.
(2) Description of the Related Art
Tractor guidance systems have been developed over a long period of time. This development shows that generally there are three elements to a guidance system for a tractor. These are broken down into (1) path sensors; (2) deviation detectors which measure the deviation as sensed by the sensor; and (3) steering means to guide the tractor responsive to the detected deviation. This particular patent relates to the path sensor.
There are many patents which relate to guiding a tractor along a furrow in the field. Examples of these would include BECK U.S. Pat. No. 4,407,716 and KNIGHT U.S. Pat. No. 1,868,360 who discloses what is believed to be basically a furrow follower. Although in a broad sense, "the path" means the line or row on the ground the tractor is to follow, in this particular application it is related only to a row of stalks.
Some of the stalk followers are called, wands, particularly if they are very light and are used to guide the tractor along a young crop wherein the stalk of the plants do not have sufficient maturity and strength to withstand greater pressures and force exerted against them.
Also, the applicants are aware of certain row followers used and mounted on harvesters, particularly one wherein a horseshoe like bracket is mounted above a stripper over one row of cotton and extends around the stripper to have a stalk feeler which runs along the stalks of cotton. The two elements feel the row, one of which feels one side of the row of cotton stalks and the other feels the other side of the row of cotton stalks. The two feeler elements are held together by the spring pressure of the horse shoe. The top or bight of the horseshoe is pivoted above the stripper mechanism. The rotational movement of the horseshoe about the pivot is used to indicate the deviation of the tractor and the row as described above. This horseshoe system would normally feel the row of stalks immediately beneath the stripper, which is to say that they would feel the stalks after the cotton bolls had been stripped from the stalk.